Inside Health

THE DOCTOR'S WORLD

By LAWRENCE K. ALTMAN, M.D.

Published: February 3, 2004

Recent reports about avian influenza in Asia have come almost daily, creating an impression that the viral disease is spreading among countries as fast as birds fly. Indeed, avian influenza has moved rapidly. The simultaneous appearance of avian influenza in eight countries, particularly in one region, is ''unprecedented,'' the World Health Organization says.

But avian influenza, or bird flu, may have been present for months in some of these countries. Now the sudden unmasking of government cover-ups and belated recognition of the disease's presence have led to the perception of a mushrooming spread.

Still, it is a crisis that illustrates a critical need for strengthening the ties between veterinary and human health experts.

The A(H5N1) strain of current concern is a mutation of the same bird flu virus that caused outbreaks among chickens in Hong Kong in 1997 and 2003, when the virus infected 20 people, 7 fatally. Now the mutated strain has caused 14 human cases, of which 11 were fatal, and led to the slaughter of 25 million birds. The human cases were believed to have resulted from direct contact with infected chickens, except for possibly two cases in Vietnam.

Infections in a Vietnamese family that were disclosed over the weekend reinforced fears among health experts that the mutated strain would swap genes with a human influenza virus to create a new virus that could cause a global epidemic. Even if scientists succeed in a crash program to develop a vaccine to prevent avian influenza in people, manufacturers lack the capacity to make enough to protect the entire world.

Most newly discovered viruses that have infected people have evolved from animals. Some, like A(H5N1), have infected a few people. But their inability to spread further among people illustrates how little is known about why some viruses can cross species barriers and then spread widely, while others are stopped cold.

The potential for migratory birds to transmit avian influenza to broader regions and the lack of strong systems to monitor animal diseases as human diseases are tracked further underscore the world's vulnerability.

''There are big holes in the global public health network to monitor the many animal diseases that have implications for humans,'' said Dick Thompson, a spokesman for the W.H.O., a United Nations agency in Geneva. ''The world needs to understand how much of a stake it has in animal diseases in third world countries.''

While the W.H.O. studies some animal diseases, countries are not required to report them to the agency. ''So we have to rely on information given to other organizations'' like the Food and Agricultural Organization of the United Nations and the World Organization for Animal Health, said Dr. Klaus Stöhr, a veterinarian and influenza expert at the W.H.O.

Experts say a number of steps are needed to improve surveillance of animal diseases. They include better laboratory facilities, less costly diagnostic tests and sharing more information among international health agencies.

While veterinarians are an integral part of the teams investigating the Asian outbreak, many experts also see a need for more of them to be integrated into public health. In addition, medical and veterinary schools need to cooperate more, said Dr. Frederick A. Murphy, dean emeritus of the University of California at Davis School of Veterinary Medicine.

Although many veterinary students are interested in public health, Dr. Murphy said, veterinary schools have been hard-pressed to change the core curriculum so that students are exposed to epidemiology and other public health programs. But experts are also urging governments to take a more informed view of the long-term consequences of hiding information. Economics underlies the secrecy. Countries that have officially reported diseases have faced sanctions including bans on their food products. ''In the quest for profits in the animal industry, human public health often comes second,'' Dr. Stöhr said.

Mr. Thompson described how health workers in a country he declined to name had taken specimens from dying animals months ago and stored them because there was no laboratory to analyze them fully. Only after publicity about the avian influenza outbreak did agricultural officials in that country send the samples to W.H.O.'s influenza laboratory network. Its virologists identified A(H5N1) in the specimens.

''Why didn't we know that months ago?'' Mr. Thompson said.

''Influenza has to have a huge impact in Africa, but we don't get much information about it there,'' Mr. Thompson said.

Influenza outbreaks in two African countries last year killed hundreds of people but attracted little attention because Africans face so many other deadly health problems, like AIDS, malaria and tuberculosis.

The same outbreaks would likely have generated headlines in the United States.

W.H.O. first learned about the mutated A(H5N1) strain in January through reports from Vietnam, then learned that birds had begun getting infected elsewhere in Asia as early as April 2003. In addition to Vietnam, the affected countries are Cambodia, China, Indonesia, Japan, Laos, South Korea and Thailand. ''We have no clue which species of bird first spread it,'' Dr. Stöhr said.

Earlier detection and effective response might have limited transmission, reduced economic losses and allowed scientists to identify the species most responsible for spreading the virus.

Infectious agents need the right kind of conditions to start epidemics. But the precise formula is far from clear.